You said:

"She's not an idiot, she knows it can't happen, she's not expecting us to--to end up married, or--" As he said it, a vivid picture formed in Harry's mind of Ginny in a white dress, marrying a tall, faceless, and unpleasant stranger.

into Japanese

「彼女白痴ではない、彼女はそれが起こることはできません彼女結婚を終了する - ことを期待していない知っているまたは -"と彼は言ったそれは、白いドレスでジニーのハリーの心の中に形成された鮮やかな画像結婚背が高く、顔、、不愉快な見知らぬ人。

Back into English

"He is no idiot woman, she is not that it will happen he terminate her marriage-does not expect to know is also-" and he said it is in a white dress formed in the mind of Ginny Harry vivid images marriage taller, face,, Obnoxious strangers.